On-surface mass tagging

ABSTRACT

The present disclosure relates to a method for detecting a compound, comprising the steps of: contacting a compound with a solid analytical surface (SAS), thereby forming an SAS with an absorbed compound; contacting the SAS with the absorbed compound with a mass tag, wherein the mass tag reacts with the absorbed compound, thereby forming an SAS with a covalently mass-tagged absorbed compound; and detecting the covalently mass-tagged absorbed compound by mass spectrometry. Also disclosed is a device for collecting breath aerosol, comprising a card or an envelope, wherein the card or the envelope comprise a tab, wherein the tab is a SAS.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication No. 62/714,954, filed Aug. 6, 2018.

GOVERNMENT SUPPORT

This invention was made with Government support under Grant No.ES017198, awarded by National Institutes of Health. The Government hascertain rights in the invention.

SUMMARY

Disclosed is a method for detecting a compound, comprising the steps of:contacting a compound with a solid analytical surface (SAS), therebyforming an SAS with an absorbed compound; contacting the SAS with theabsorbed compound with a mass tag, wherein the mass tag reacts with theabsorbed compound, thereby forming an SAS with a covalently mass-taggedabsorbed compound; and detecting the covalently mass-tagged absorbedcompound by mass spectrometry. Also disclosed is a device for collectingbreath aerosol, comprising a card or an envelope, wherein the card orthe envelope comprise a tab, wherein the tab is a SAS.

BACKGROUND

A solid analytical surface (SAS) is a solid surface on which collectedcompounds begin a detection process such as mass tag mass spectrometry.It is important to detect sorbed (absorbed or adsorbed) compoundscollected on a SAS. Examples of the importance of an SAS detectionprocess are as follows. Detection of sorbed compounds from foods,regardless of the mode of collection of the compounds have on a SAS(such as from air that carries a food odor, from a liquid that is a foodor has contacted food, or by direct or indirect contact with a surfaceof interest [primary surface] of a solid or semi-solid food), can helpevaluate the freshness, quality, expiration or spoilage of a food.Similarly, detection of SAS-sorbed compounds from alcoholic beveragesincluding wine and beer can help guide production, ingredients,blending, and storage. Similarly, detection of SAS-sorbed compounds fromcosmetics, including perfumes, can help evaluate ingredients, quality,reproducibility, safety and appeal to consumers. Similarly,SAS-detection of sorbed compounds from containers for foods can helpevaluate leaching of contaminants. Similarly, detection of SAS-sorbedcompounds from household air can help reveal indoor toxic exposures.Similarly, detection of SAS-sorbed compounds from human or otherbiological samples, such as saliva, tears, breath, skin, blood, urine,or feces can help assess health and disease, such as monitoring of drugsincluding those of multi-substance abuse, and therapy for drug abusers.Similarly, detection of airborne compounds on a primary surface, viaswabbing this surface with a SAS, can help reveal illicit transport ofdrugs or people, or reveal the identity of chemicals or other threatagents released by a terrorist or enemy. SAS testing can also be usefulin forensics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows two mass spectra related to detection of C₁-C₂₆ fatty acidsin breath according to General Procedure Using CAX-B. The blank is acontrol filter paper SAS (i.e., filter paper not exposed to breath).

FIG. 2 shows two mass spectra related to detection of prostaglandins inbreath according to General Procedure Using CAX-B. The upper massspectrum is from a blank SAS, as above.

FIG. 3 shows two mass spectra related to detection of aspirin,hydrolyzed aspirin, and creatinine in breath according to GeneralProcedure using CAX-B. The blank is as above.

FIG. 4 shows three mass spectra related to detection of electrophiliccompounds in breath according to General Procedure Using CAX-H.

FIG. 5 shows a device comprising filter paper compacted in a syringe forelution of mass-tagged compounds prior to detection.

FIG. 6 shows a tilt elution technique where the filter paper is in awatch glass or petri dish.

FIG. 7 shows a tube elution device, in the case where the rolled SASprotrudes from the tube.

FIG. 8 shows a schematic depiction of a surface tagging reaction on anSAS with a CAX reagent.

FIG. 9 shows a schematic depiction of an analytical microfluidic chipfor analysis via an SAS.

FIG. 10 shows two mass spectra related to preliminary detection ofcannabinoids in breath by CAX-B/MALDI-TOF-MS, where the subject whosmoked a marijuana cigarette breathed on a filter paper for 5 minutesand the filter paper was tested according to General Procedure UsingCAX-B.

FIG. 11 shows two mass spectra related to preliminary detection ofcannabinoids in breath by CAX-B/MALDI-TOF-MS, where the subject whosmoked a marijuana cigarette breathed on a filter paper for 5 minutesand the filter paper was tested according to General Procedure UsingCAX-B, except that detection was by infusion LTQ Orbitrap XL-MS.

FIG. 12 shows two mass spectra related to detection of compounds in theair above a rotten cob of corn, where a filter paper was kept in aplastic bag along with the corn for 10 minutes, but without and directcontact. The filter paper then was subjected to General Procedure UsingCAX-B.

FIG. 13 shows structures of CAX reagents used in General Procedure.

FIG. 14 shows a system for elution of mass-tagged compounds from filterpaper, Method 2.

FIG. 15 shows a MALDI-TOF-MS spectrum of an untreated (standard) sample.

FIG. 16 shows a system for elution of mass-tagged compounds from filterpaper, Method 1.

FIG. 17 shows a MALDI-TOF-MS spectrum of a sample obtained by Method 1.

FIG. 18 shows a MALDI-TOF-MS spectrum of a sample obtained by Method 2.

FIG. 19 shows a schematic depiction of Method 3 of sample preparation.

FIG. 20 shows a MALDI-TOF-MS spectrum of a sample obtained by Method 3.

FIG. 21 shows a MALDI-TOF-MS spectrum of a sample obtained by Method 4.

FIG. 22 shows a MALDI-TOF-MS spectrum of a sample obtained in theprocess of detection of acebutalol using trifluoromethyl diazirinereagent.

FIG. 23 shows a MALDI-TOF-MS spectrum of a sample obtained in theprocess of detection of cannabinoids standard mix using CAX-B andammonium hydroxide as a base.

DETAILED DESCRIPTION

A SAS can be organic or inorganic. It can be single layered ormultilayered or mosaic or combinations of these comprising of ceramic,or carbon, or metal, or metal oxide, or surface treated material, orsurface coated material, or silica, or glass, or quartz, orpolyethylene, or polypropylene, or polycarbonate, or polyester, orbakelite, or crystals of salts, or surface of a stone or ice, or a drygel, or zeolite,or polyfluorocarbon, or chitin, or silicon, or mica, orcellulose, or modified cellulose. It can be polar or nonpolar or mixed.It can be ionic or nonionic. It can be porous or nonporous. It can be asemi-solid. It can be an electret. It can be a particle or compriseparticles or fibers or wires. It can comprise combinations of these. ASAS can be flexible, such as a filter paper or soft membrane. Forexample, a SAS can comprise a flat surface as provided by a filter paperor membrane.

Collection of airborne compounds can be done passively or actively, whenthe air is blown on or through the SAS. Compounds that have accumulatedfrom air onto some other surface [primary surface], such as table orwall, can be swabbed by the SAS to pick up the compounds. The compoundsmay come from a mist or airborne microorganisms. Compounds from a liquidcan be collected on a SAS by adding one or more drops of the liquid tothe SAS, or dipping the SAS into the liquid. The liquid can be blood,urine, beer or juice, for example. A SAS can be touched to a piece offood such as cheese, lettuce, fish, or steak, for example, to collectcompounds for detection. A SAS can be touched to the skin or tongue ofan animal or person, to the window or seat of a car, or to a suitcase tocollect compounds for detection. A SAS can be used to help diagnose skinconditions such as melanoma. The skin, preferably after cleaning, can bewetted with a liquid such as isopropanol before a SAS is touched orpressed to it, to enhance collection of metabolites. A SAS can betouched to tissue during surgery to help define the cancerous zone.

A diversity of detection techniques is used to measure sorbed substanceson surfaces. Mass spectrometry can provide both qualitative andquantitative information. In this technique, heat, plasma (as in DART),an electrospray (as in DESI) or an organic solvent can be used torecover a sorbed compound from a SAS for detection. When heat, plasma orelectrospray is employed, sorbed compounds can be directly volatilizedfor entry into the mass spectrometer. If the sorbed compounds are elutedfrom a SAS with an organic solvent, three choices for the subsequentsteps are common, and they may be combined to some degree. 1. Directinjection into the mass spectrometer, perhaps via a chromatographicinterface; 2. Evaporation of solvents and redissolving of the residue toprovide a more concentrated sample of compounds for introduction intothe mass spectrometer; and 3. Derivatization of the eluted oreluted/evaporated or eluted/evaporated/redissolved compounds to improvethe volatility or sensitivity of the compounds before they areintroduced into the mass spectrometer.

Mass tag mass spectrometry is sometimes used for detection. In thistechnique, a target compound or type of compound is reacted covalentlywith a reactive reagent called a “mass tag” to form a covalent masstag-compound product that is then detected. The main or usual purpose ofthe mass tag is to increase the response of the target substance in themass spectrometer. The term “mass tag” refers to a reagent used inderivatization prior to detection by mass spectrometry. Particularlyuseful is a cationic xylyl (CAX) mass tag since it is ananchimeric-assisted neutral loss mass tag, as has been described (Wang,P., Zhang, Q., Yao, Y., Giese, R. W. [2015] Cationic Xylene Tag forIncreasing Sensitivity in Mass Spectrometry, J. Am. Soc. Mass Spectrom.26, 1713-1721, DOI: 10.1007/s13361-015-1200-4). Also useful arepolyfluoroorganic reagents, such as pentafluorobenzyl bromide, and itsp-alkoxy or para-H analogues, for detection by electron capture massspectrometry (Giese, R. W. [1997] Detection of DNA Adducts by ElectronCapture Mass Spectrometry, Chem. Res. in Toxicology, 10, 255-270; Giese,R. W. [2000] Electron-capture mass spectrometry: recent advances, J.Chromatogr., 892, 329-346.).

Disclosed is a novel process for the detection of sorbed compounds on aSAS by mass spectrometry involving the use of mass tags. In someembodiments, mass tags are quaternary amines and polyfluoroorganiccompounds. In one instance of the disclosed method, derivatization isconducted directly on a SAS containing the sorbed compound(s),especially under an energy-rich conditions. This gives a quick and/orconvenient derivatization. In certain embodiments, energy types aremicrowaves and UV. Microwave CAX mass tagging of compounds (Analytes) ona filter SAS is illustrated in FIG. 8. An evaporative derivatizationresults in solvent on the SAS evaporating during the reaction. Anelution solvent then can be employed to recover the mass tag-derivatizedcompounds for detection. It is useful to elute the mass-tagged compoundswith a solvent in which the mass-tagged compounds are more soluble thanthe residual mass-tag, hydrolyzed mass-tag, or mass-tag that has beenreacted with a scavenger. A scavenger is a chemical that convertsresidual mass-tag to an alternative product. This enables the mass tagderivatives of the sorbed compounds to be detected with minimalinterference from residual mass-tag reagent. The present disclosure alsocovers the case in which a SAS traps residual mass-tag reagent in acovalent or noncovalent way. For example, a mass tag can react both withthe sorbed compound on the SAS surface, and the SAS surface itself, tominimize free, residual mass tag after the reaction. A catalyst orcatalytic SAS can be used to accelerate the derivatization reaction.

A diversity of energy sources can be used to accelerate the reaction ofthe mass tag with the sorbed compounds on an SAS, such as: hot surface(e.g. place the SAS on a hot surface, or position the SAS under a hotsurface); microwaves (e.g. place the SAS in a microwave oven;), UV (usedfor nitrene and carbene yielding mass tags), IR, artificial visiblelight (used especially for a colored SAS that can absorb visiblephotons), sunlight, heat gun (provides a flow of hot air), ultrasound,electricity (passed through a SAS); inductive heating (SAS is a metal oris nearby or in contact with a metal that is subject to inductiveheating; laser (especially when a matrix substance is present as inMALDI mass spectrometry); and an exothermic chemical reaction (conductedas a secondary reaction near the surface, as by employing cordite,thermite or centralite).

Disclosed is use of mass tags having functional groups with restrictedreactivity so that sub-classes of sorbed compounds having complementaryfunctional groups can be detected selectively. Examples of suchfunctional groups on mass-tags providing specific detection are anilino,hydrazide, activated carboxyl, hydroxylamine, diazonium, and haloacetyl.The present disclosure additionally covers mass-tags with broadspecificity for sorbed compounds to be detected. Examples of broadselectivity reagents, or types of such reagents, are as follows: aquaternary amine benzylbromides such as CAX-B (Wang et al., 2015) thatcan label active hydrogen sites (readily ionizable) on sorbed compounds;pentafluorobenzyl bromide that can similarly label active hydrogensites, and carbenes or nitrenes that can insert into the chemical bondsof compounds. Carbene and nitrene reactive groups are generated under UVconditions. Broad selectivity can also be achieved by using intensechemical conditions such as cesium hydroxide, phase transfer catalysis,or crown ethers (Dueno, E. E., Che, F., Kim, S-I, Jung, K. W. [1999]Cesium Promoted O-Alkylation of Alcohols for the Efficient EtherSynthesis, Tetrahedron Letters, 40, 1843-1846).

After the derivatization reaction is conducted on the SAS, it isconvenient to elute the products of interest by folding a soft SAS intoa tube shape; insert the folded, tube-shaped soft SAS into a syringe;compact the soft SAS using a syringe plunger down to the bottom of thesyringe; add an elution solvent to the compressed soft SAS; and recoverthe elution solvent containing the mass-tagged compounds of interest inone of the following ways: (1) let solvent flow out by gravity; (2)force the solvent out with the aid of the plunger; or (3) force thesolvent out by centrifugation. This concept is illustrated in FIG. 5.

Another convenient way to elute the mass-tagged compounds from an SASsuch as a filter paper is to tilt the container of an SAS, such as aPetri dish or water glass, so that elution solvent added to the uppertip of the SAS flows through the SAS and comes out at the bottom tip ofSAS containing the tagged compound(s) of interest. The eluted solutionthen can undergo analysis by chromatography-mass spectrometry or massspectrometry. This elution technique can also be made faster bycentrifugation. This concept is illustrated in FIG. 6.

Another convenient way to elute the mass-tagged compounds from an SASsuch as a filter paper is to roll the SAS and insert it into a tube withsome of the roll sticking out the lower end of the tube. This concept isillustrated in FIGS. 7 and 16. Once the elution solvent has moved themass-tagged compound(s) of interest onto the part of the surface thatprotrudes from the tube, this part can be cut off (before or after ithas dried), and the products taken from it as by elution. One can alsoput the rolled SAS into the tube with none of the roll sticking out, andrecover mass-tagged compounds by elution. This concept is illustrated inFIG. 14. Potentially this latter elution also can be accelerated bycentrifugation.

Because the CAX mass tags have a positive charge and are also nonpolar,one can conduct large-volume liquid injection of eluted CAX mass-taggedcompounds from a SAS into a chromatography column under weak solventelution conditions to achieve enrichment of the CAX mass-taggedcompounds. Such enrichment can take place by hydrophobic retention whenthe sample is contained in or diluted with water prior to injection.Enrichment can also be done by cation exchange chromatography. Forpolyfluororganic mass-tagged compounds, enrichment can take placehydrophobically or via fluorous solid phase extraction. For both kindsof mass tags, enrichment can take place on a molecular-imprinted polymer(MIP). A MIP is best directed at a part of the mass tag other than thequaternary amine or polyfluoro part of the residual tag or tag sideproducts to increase purification of desired products. For apolyfluoorganic tag-compound product, detection is best accomplished bygas chromatography electron capture mass spectrometry.

In some embodiments, conditions for derivatization of sorbed compounds(sorbed analytes) on a SAS with a quaternary amine as a mass tagcomprise adding such a mass tag directly to the SAS, and then subjectingthe SAS to microwaves in a microwave oven, such as 2 minutes on fullpower. This tends to provide evaporative derivatization conditions,which removes the solvent while accelerating the reaction. Indeed, thisestablished a new technique for derivatization: evaporative phasetransfer on-surface derivatization with a quaternary amine reagent. Fivekey advantages of this new technique are as follows: (1) speed; (2)convenience; (3) solvent removal or reduction in amount; (4) broad scopefor analytes (even alcohols are derivatized); and (5) can greatlyincrease response for analytes in a mass spectrometer. The reaction ofthe mass tag can take place with the compound-containing SAS in a dish,plate, open tube, test tube or other container. The SAS can be suspendedby a pin or clip for this reaction. Elution of the mass-tagged compoundswith an organic solvent followed by direct, large volume injection intoa chromatography-mass spectrometry system can provide an overall rapidanalysis. The mass-tagged, sorbed compounds on the SAS also can bedetected by applying a MALDI matrix such as α-cyano-4-hydroxycinnamicacid to the surface and then subjecting this surface to matrix-assistedlaser desorption ionization mass spectrometry.

Suitable for detection of a CAX-labeled compound in this disclosure isan electrospray ionization mass spectrometer, especially with a liquidchromatograph at the front end. The mass spectrometer can also be amatrix-assisted laser desorption ionization (MALDI) mass spectrometer. Asolution containing a mass-tagged compound eluted off a SAS can beanalyzed directly by this latter technique, without any intermittentchromatography.

A SAS with collected compounds can be analyzed in a microfluidic chipsuch as that similar to an Agilent Microfluidic Chip, a Thermo FisherScientific Zip Chip, or a New Objective PicoChip. Such a SAS can undergothe mass tagging reaction before or after it is incorporated into orinterfaced with a chip. A SAS can be set up as part of a chip prior tocollection of compounds (SAS-Chip), where the SAS-Chip is subjected tothe following steps: (1) collect compounds to be detected, on theSAS-Chip; (2) undergo mass tagging reaction; and (3) connect to a massspectrometer or liquid chromatography mass spectrometer for detection. Achromatography column can be part of the chip or the mass spectrometer.FIG. 9 illustrates the concept of loading a SAS into a microfluidic chipfollowed by elution, preferably by means of enrichment chromatographyon-chip into a mass spectrometer.

One aspect of the present disclosure relates to a method for detecting acompound, comprising the steps of: contacting a compound with a solidanalytical surface (SAS), thereby forming an SAS with an absorbedcompound; contacting the SAS with the absorbed compound with a mass tag,wherein the mass tag reacts with the absorbed compound, thereby formingan SAS with a covalently mass-tagged absorbed compound; and detectingthe covalently mass-tagged absorbed compound by mass spectrometry.

In certain embodiments, the SAS comprises a biopolymer, an organicpolymer, an inorganic substance, or a metal.

In some embodiments, the compound is a biomolecule, drug, or a syntheticmolecule.

In certain embodiments, the compound is a gaseous compound in air orbreath.

In certain embodiments, the method further comprises, prior to thedetection step, contacting the SAS with the covalently mass-taggedabsorbed compound with a solvent, thereby forming a solution comprisingthe solvent and the covalently mass-tagged absorbed compound; whereinthe solvent is selected from the group consisting of methanol, ethanol,isopropanol, acetone, methylisobutylketone, ethyl acetate, acetonitrile,chloroform, dichloromethane, ethylene dichloride, carbon tetrachloride,hexane, cyclohexane, toluene, benzene, xylene, mesitylene, anisole,nitrobenzene, chlorobenzene, dimethylformamide, dioxane, diethyl ether,tetrahydrofuran, 2-methyl tetrahydrofuran, acetic acid, formic acid,propanoic acid, aqueous buffer, salt solution, water, and a combinationof any of them.

In some embodiments, the compound is from a food, animal, human, or acell culture.

In certain embodiments, the mass tag is a molecule comprising a moietyselected from the group consisting of quaternary amine group, a benzylgroup, and a polyfluoroorganic group, and the polyfluoroorganic grouphas at least three fluorine atoms.

In some embodiments, the mass tag is a molecule comprising a moietyselected from the group consisting of

—NHNH₂, —C(═O)Hal, —NHOH, —C— (carbene group), —N (nitrene group), —N₂ ⁺(diazonium group), and —C(═O)CH₂Hal; Hal is Cl, Br, or I; and R issubstituted or unsubstituted C₁₋₆ alkyl, C₁₋₆ haloalkyl, or C₆₋₁₂ aryl.

In certain embodiments, the SAS comprises an ion exchange surface or ahydrophobic surface.

In some embodiments, the method further comprises folding, compacting orshredding the with the covalently mass-tagged absorbed compound prior tocontacting the SAS with the covalently mass-tagged absorbed compoundwith the solvent.

In certain embodiments, the mass tag reacts with the absorbed compoundupon exposure to electromagnetic radiation, such as microwave radiationor UV radiation.

In some embodiments, the reaction takes place under evaporativeconditions.

In certain embodiments, the compound is comprised by a liquid sample ora solid sample.

In some embodiments, the mass tag is an anchimeric-assisted neutral losscationic reagent.

One aspect of the present disclosure relates to a device for collectingbreath aerosol, comprising a card or an envelope, wherein the card orthe envelope comprise a tab, wherein the tab is a SAS.

In certain embodiments, the tab comprises filter paper, a membrane, or adisc, wherein the disc comprises an inorganic substance.

In some embodiments, the tab is attached to the card or the envelope,thereby forming an attachment, wherein the attachment comprises astaple, fold, pin, glue, slot, or pocket.

In some embodiments, the card comprises cellulose or an organic polymer.

In certain embodiments, the card has dimensions of about 1 inch×4 inch.

In some embodiments, the SAS comprises an electret.

EXAMPLES Example 1. Use of On-Surface Mass Tagging for Analyte Detection

-   1A. A threat chemical at disaster site is identified by (1) swabbing    the surface of a building with a SAS, (2) conducing derivatization    by adding a solution of CAX-B to the SAS and heating in a microwave    oven for 2 minutes or less, (3) eluting the resulting CAX-tagged    compounds with an organic solvent such as acetonitrile or methanol,    and (4) injecting into a liquid chromatography mass spectrometer    system or a liquid chromatography tandem mass spectrometer system.-   1B. A meat is found to be spoiled, infectious, or poisoned by    patting it with an SAS and following steps (2)-(4) of Example 1A.-   1C. A subject is found to have early lung cancer by breathing onto    an SAS for 2 minutes, and following steps (2)-(4) of Example 1A.-   1D. A subject is found to have tuberculosis by following steps of    Example 1C.-   1E. A subject is found to be under the influence of marijuana when    driving erratically by following the steps of Example 1C, leading to    the detection of one or more cannabinoids or cannabinoid    metabolites.-   1F. A person who committed a crime is identified by swabbing him    with an SAS; independently swabbing various surfaces (e.g., window,    table, chair, door) at the crime scene; following steps (2)-(4) of    Example 1A; and detecting a similar pattern of metabolites on both    SASs.-   1G. A subject is characterized in terms of multi-substance abuse by    following the steps of Example 1C and detecting multiple drugs of    abuse.-   1H. The experiment of Example 1A, 1B, or 1C is done with a CAX    reagent in which a quinuclidine moiety is present rather than a    triethylamine moiety.-   11. The experiment of Example 1A, 1B, or 1C where the sample-exposed    SAS is dried in a microwave oven prior to its reaction with CAX-B.-   1J. The experiment of Example 1A, 1B, or 1C where the sample-exposed    SAS is loaded into syringe or tube prior to its reaction with CAX-B.    General Procedure Using CAX-A

Breath-exposed filter paper (4.25 cm diameter, Fisher brand catalog No.09-8-3-6A) was treated with 100 μL of Solution A to cover the entirearea. Then place on a watch glass (Corning, Inc. 998575) and heated in ahousehold microwave oven (700 w) for 2 min. Upon cooling to roomtemperature, it was rolled and stuffed into a glass tube (Fisher catalogNo. 13-678-20D) as shown in FIG. 14. 1 mL of CHCl₃ was added dropwise.The solvent was collected in the vial below as shown in FIG. 14. CHCl₃was evaporated under vacuum and residue was dissolved in 100 μL CH₃CN.Five microliters from this vial were taken and added to 20 μL of aα-cyano-4-hydroxycinnamic acid (CHCA) matrix solution (5 mg/mL in 50%aq. CH₃CN), and 0.7 μL of the resulting mixture was loaded per spot on aMALDI-TOF plate, and the MALDI-TOF plate was analyzed in a SCIEX 5800MALDI-TOF/TOF mass spectrometer in the MALDI-TOF-MS mode with 400 shotsper spectrum.

-   Where: Solution A=CAX-A (1 mg)+NaCNBH₃ (10 mg) in 1 mL of 50% aq.    CH₃CN.    General Procedure Using CAX-B

Breath-exposed filter paper (4.25 cm diameter, Fisher brand catalog No.09-8-3-6A) was treated with 100 μL of Solution B to cover the entirearea. Then place on a watch glass (Corning, Inc. 998575) and heated in ahousehold microwave oven (700 w) for 2 min. Upon cooling to roomtemperature, it was rolled and stuffed into a glass tube (Fisher catalogNo. 13-678-20D) as shown in FIG. 14. 1 mL of CHCl₃ was added dropwise.The solvent was collected in the vial below as shown in FIG. 14. CHCl₃was evaporated under vacuum and residue was dissolved in 100 μL CH₃CN.Five microliters from this vial were taken and added to 20 μL of theCHCA matrix solution (5 mg/mL in 50% aq. CH₃CN), and 0.7 μL of theresulting mixture was loaded per spot on a MALDI-TOF plate and tested asdescribed above.

-   Where: Solution B=CAX-B (1 mg)+triethylamine (10 μL) in 1 mL of 50%    aq. CH₃CN.    General Procedure Using CAX-H

Breath-exposed filter paper (4.25 cm diameter, Fisher brand catalog No.09-8-3-6A) was treated with 100 μL of Solution H to cover the entirearea. Then place on a watch glass (Corning, Inc. 998575) and heated in ahousehold microwave oven (700 w) for 2 min. Upon cooling to roomtemperature, it was rolled and stuffed into a glass tube (Fisher catalogNo. 13-678-20D) as shown in FIG. 14. 1 mL of CHCl₃ was added dropwise.The solvent was collected in the vial below as shown in FIG. 14. CHCl₃was evaporated under vacuum and residue was dissolved in 100 μL CH₃CN.Five microliters from this vial were taken and added to 20 μL of theCHCA matrix solution (5 mg/mL in 50% aq. CH₃CN), and 0.7 μL of theresulting

-   Where: Solution H=CAX-H (1 mg) in 1 mL of 50% aq. CH₃CN.

Example 2. Optimizing Recovery of Authentic Product (Methods 1-4)

General Experimental Details

Solution A2: CAX-A 1.2 mg/mL in 50% aq. CH₃CN.

Solution B2: CAX-A-benzaldehyde product (FIG. 15) 1.2 mg/mL in 50% aq.CH₃CN.

Solution C2: 5 mg of NaCNBH3 in 250 μL of 50% aq. CH₃CN.

Solution D2: 25 μL of solution A2+25 μL of solution B2 were added tosolution C2 and stirred for 1 min.

Blank sample (Untreated): 100 μL of solution D2 was placed in a 1 mLvial and evaporated to dryness under vacuum. The residue was dissolvedin 400 μL of CH₃CN; 5 μL of the CH₃CN solution was added to 20 μL of theCHCA matrix solution (5 mg/mL in 50% aq. CH₃CN), and 0.7 μL of theresulting mixture was loaded per spot on a MALDI-TOF plate and tested asdescribed above, yielding data shown in FIG. 15.

Method 1

100 μL of solution D2 was added to wet a filter paper (4.25 cm diameter,Fisher brand catalog No. 09-8-3-6A). The paper was placed on a watchglass (Corning, Inc. 998575) and heated under microwave conditions for 2min. After cooling, it was placed into a cut glass tube (Fisher catalogNo. 13-678-20D), as shown in FIG. 16. About 1 cm portion of the paperwas protruding out of the tube. To this tube was added 500 μL of CH₃CN,when the solvent reached the bottom of the paper, the lower protrudingportion was cut, allowed to air dry, and the paper was transferred to avial containing 400 μL of CH₃CN; 5 μL of the CH₃CN solution was added to20 μL of the CHCA matrix solution (5 mg/mL in 50% aq. CH₃CN), and 0.7 μLof the resulting sample was loaded per spot on a MALDI-TOF plate andtested as described above. MALDI-TOF-MS spectrum of the sample is shownin FIG. 17.

Method 2

100 μL of solution D2 was added to wet a filter paper (4.25 cm diameter,Fisher brand catalog No. 09-8-3-6A). The paper was placed on a watchglass (Corning, Inc. 998575) and heated under microwave conditions for 2min. After cooling, it was rolled up and plugged into a glass tube(Fisher catalog No. 13-678-20D), as shown in FIG. 14. To this tube wasadded 1 mL CHCl₃ and the solvent was collected in the vial below. CHCl₃was evaporated under vacuum, and the residue was dissolved 400 μL ofCH₃CN; 5 μL of the CH₃CN solution was added to 20 μL of the CHCA matrixsolution (5 mg/mL in 50% aq. CH₃CN), and 0.7 μL of the resulting samplewas loaded per spot on a MALDI-TOF plate and tested as described above.MALDI-TOF-MS spectrum of the sample is shown in FIG. 18.

Method 3

The sample was prepared according to the steps depicted in FIG. 19.

-   Step 1: A piece of filter paper (1.5″×3.0″) was cut;-   Step 2: The top portion of the paper was folded along the arbitrary    fold line;-   Steps 3 and 4: 100 μL of solution D2 was added to an oval zone on    the folded filter paper;-   Step 5: The paper was placed on a watch glass (Corning, Inc. 998575)    and heated under microwave conditions for 2 min;-   Step 6: The paper was cooled;-   Step 7: The paper was placed into a glass chamber (Pyrex catalog No.    1680-4080; 40×80 mm) and the mixture was eluted using CH₃CN as a    mobile phase; the solvent was allowed to reach the top of the filter    paper;-   Step 8: About 2 cm of the top portion of the filter paper was cut    (product enriched zone) and allowed to air dry;-   Step 9: The paper was transferred to a vial containing 400 μL of    CH₃CN;-   Step 10: 5 μL of the CH₃CN solution was added to 20 μL of the CHCA    matrix solution (5 mg/mL in 50% aq. CH₃CN), and 0.7 μL of the    resulting sample was loaded per spot on a MALDI-TOF plate and tested    as described above. MALDI-TOF-MS spectrum of the sample is shown in    FIG. 20.    Method 4

100 μL of solution D2 was added to wet a filter paper (4.25 cm diameter,Fisher brand catalog No. 09-8-3-6A). The filter paper was placed on awatch glass (Corning, Inc. 998575) and heated under microwave conditionsfor 2 min. After cooling the filter paper was added to a fluted phaseseparation filter paper and washed with 2 mL of CHCl₃. The solvent wascollected in the vial below. CHCl₃ was evaporated under vacuum, and theresidue was dissolved in 400 μL of CH₃CN; 5 μL of the CH₃CN solution wasadded to 20 μL of the CHCA matrix solution (5 mg/mL in 50% aq. CH₃CN),and 0.7 μL of the resulting sample was loaded per spot on a MALDI-TOFplate and tested as described above. MALDI-TOF-MS spectrum of the sampleis shown in FIG. 21.

Example 3. Derivatization and Detection of Acebutolol UsingTrifluoromethyl Diazirine Reagent

Solution A3: trifluromethyl diazirine reagent (2 μL/mL) andtriethylamine (100 μL/mL) in 50% aq. CH₃CN) was stored in an amber vialfor 4 h before use at rt.

Acebutolol solution: 1.7 mg/mL in 50% aq. CH₃CN.

A filter paper disc (5 cm in diameter) was wetted with 100 μL ofsolution A3 and 100 μL of acebutolol solution and kept under UV light(350 nm) for 12 h at r.t. The distance between the UV lamp and the paperwas about 2.5 cm. The paper disc was then washed using 2 mL of 50% aq.CH₃CN and 2 mL of isopropanol to give an extract. The extract wasseparated using a centrifuge. The solvents were removed under vacuumfollowed by reconstitution of residue by addition of 500 μL of 50% aq.CH₃CN; 2 μL of the CH₃CN solution was added to 500 μL of 5% CHCA matrixsolution. 0.55 μL of the resulting sample was loaded per spot on aMALDI-TOF plate and tested as described above. MALDI-TOF-MS spectrum ofthe sample is shown in FIG. 22. The spectrum demonstrates the presenceof a molecular ion for the acebutolol-trifluromethyl diazirine reagentadduct (m/z 608.367), as well as a fragmentation product (m/z 507.404)resulting from the loss of an Et₃N molecule.

Example 4. Detection of Cannabinoids Standard Mix with CAX-B andAmmonium Hydroxide as a Base

Reagents:

-   CAX-B solution: 1.3 mg/mL in 50% aq. CH₃CN;-   Ammonium hydroxide: 30% aq. solution-   Solution A4: 80 μL of CAX-B solution mixed with 20 μL of ammonium    hydroxide solution (used within 1 min)-   Cannabinoids standard mix: 1 mg/mL (RESTEK, Catalog No. 34014)

Procedure:

2 μL of the Cannabinoids standard mix solution was added to a filterpaper (Fisherbrand P4 qualitative, Diameter=4.25 cm), and allowed to dryat room temperature. 100 μL of solution A4 was added to the paper, andthe paper was placed on a watch glass (Corning, Inc. 998575) and heatedunder microwave conditions for 2 min. The filter paper was removed usingclean forceps and placed in a BD syringe (Mfr. No. 301077, 3mL) andpressed using the syringe plunger to form a plug (FIG. 5). The plungerwas withdrawn, 400 μL of CH₃CN were added to the plug, and solvent wascollected (under gravity) in a glass vial below. The solvent wasevaporated to give a residue which was dissolved in 20 μL of the CHCAmatrix solution (5 mg/mL in 50% aq. CH₃CN), and 0.7 μL of the resultingsample was deposited per spot on MALDI-TOF plate and tested as describedabove. MALDI-TOF-MS spectrum of the sample is shown in FIG. 23. Thespectrum demonstrates the presence of a molecular ion for theCAX-B-derivatized cannabinol (m/z 514.368), CAX-B-derivatizedcannabidiol (m/z 518.399), and CAX-B-derivatizeddelta-9-tetrahydrocannabinol (m/z 518.399).

We claim:
 1. A method for detecting a compound, comprising the steps of:contacting a compound with a solid analytical surface (SAS), therebyforming a SAS with an absorbed compound; contacting the SAS with theabsorbed compound with a mass tag, wherein the mass tag reacts with theabsorbed compound, thereby forming a SAS with a covalently mass-taggedabsorbed compound; and detecting the covalently mass-tagged absorbedcompound by mass spectrometry; wherein the mass tag is


2. The method of claim 1, wherein the SAS comprises a biopolymer, anorganic polymer, an inorganic substance, or a metal.
 3. The method ofclaim 1, wherein the compound is a biomolecule, drug, or a syntheticmolecule.
 4. The method of claim 1, wherein the compound is a gaseouscompound in air or breath.
 5. The method of claim 1, further comprising,prior to the detection step, contacting the SAS with the covalentlymass-tagged absorbed compound with a solvent, thereby forming a solutioncomprising the solvent and the covalently mass-tagged absorbed compound;wherein the solvent is selected from the group consisting of methanol,ethanol, isopropanol, acetone, methylisobutylketone, ethyl acetate,acetonitrile, chloroform, dichloromethane, ethylene dichloride, carbontetrachloride, hexane, cyclohexane, toluene, benzene, xylene,mesitylene, anisole, nitrobenzene, chlorobenzene, dimethylformamide,dioxane, diethyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran,acetic acid, formic acid, propanoic acid, aqueous buffer, salt solution,water, and a combination of any of them.
 6. The method of claim 1,wherein the compound is from food, an animal, a human, or a cellculture.
 7. The method of claim 1, wherein the SAS comprises an ionexchange surface or a hydrophobic surface.
 8. The method of claim 5,further comprising folding, compacting or shredding the SAS with thecovalently mass-tagged absorbed compound prior to contacting the SASwith the covalently mass-tagged absorbed compound with the solvent. 9.The method of claim 1, wherein the mass tag reacts with the absorbedcompound upon exposure to electromagnetic radiation.
 10. The method ofclaim 9, wherein the mass tag reacts with the absorbed compound uponexposure to microwave radiation.
 11. The method of claim 9, wherein themass tag reacts with the absorbed compound upon exposure to ultravioletradiation.
 12. The method of claim 1, wherein the compound is comprisedby a liquid sample or a solid sample.